The present invention relates to an optical recording device.
There has been invented and demonstrated an optical recording system in which the writing laser beam is focused to a very small spot less than one micrometer in diameter on a disk made of or coated with a photosensitive medium and spinned at a predetermined velocity so that the data can be recorded at a higher degree of density in terms of variable density or surface irregularities.
Various optical disk systems have been well known which can reproduce the data or signals optically recorded at a higher degree of density in a manner as described above. In the production of the prerecorded optical disks, the above described optical recording system has been used. The recorded data are video, audio and digital signals.
According to the above-described optical recording system, the writing laser beam is focused on the recording thin film coated over the disk so that the laser beam melts and evaporates a small area on the disk, leaving a hole or pit or changing the reflection coefficient. To put in another way, the thermal energy of the writing laser beam causes the variation of the optical properties of a recording medium.